The amount of data that can be stored on magnetic media, e.g., tapes or discs, can be increased by increasing the bit and track density of the magnetic media. This in turn requires magnetic heads that are capable of reading and writing at these increased bit and track densities. One such head is a thin-film head.
Thin-film heads, however, are highly sensitive to wear caused by contact between the head and the moving magnetic media. This wear causes a washing out or dishing of the center of the head surface, resulting in decreased accuracy of the head during reading and writing. While the larger ferrite heads can generally withstand as much as 50 .mu.m of wear, the smaller thin-film heads can tolerate only about 1-2 .mu.m of wear before their accuracy during reading and writing is affected.
Future generations of thin-film heads may place the read and write functions in the same physical gap to reduce alignment tolerances and thereby achieve greater track densities. This would exacerbate the problems caused by wear of the head.
The manufacture of thin-film magnetic recording heads typically begins with a ceramic substrate comprised of an Al.sub.2 O.sub.3 -TiC composite monolithic wafer on which electromagnetic circuitry is deposited through a combination of sputter deposition, vapor deposition, electroplating, and photolithography. Each magnetic head element requires about ten square millimeters of substrate surface and therefore several hundred head elements can be formed simultaneously on a single substrate wafer. Other heads, known as micro and sub-micro heads, are substantially smaller so that several thousand such heads can be formed simultaneously on the wafer surface. After the transducers are formed on the substrate surface, the wafer is cut into the individual head elements, and precision lapped and polished to form the interface with the storage media. Typically, a 10-15 .mu.m thick coating of non-conductive, amorphous aluminum oxide (a-Al.sub.2 O.sub.3) is sputtered onto the substrate to provide electrical isolation prior to deposition of the transducer elements. This electrically insulating coating can require 10-15 hours to deposit using very expensive equipment, thereby adding substantially to the time and cost required to produce a magnetic head. The deposited a-Al.sub.2 O.sub.3 layer must then be lapped back and polished to achieve the desired surface finish. The resultant a-Al.sub.2 O.sub.3 coating is substantially softer than the Al.sub.2 O.sub.3 -TiC substrate and therefore wears at a faster rate causing poor head performance due to the recession of the coating and attached transducer elements.
It would be desirable to have a thin-film head assembly that was more resistant to wear by magnetic media and less expensive to make than currently available thin-film heads.